Pneumato-electric tracker-bar for musical instruments.



C. W. DORRICOTT. PNBUMATC ELECTRIC TRACKER BAR FC5 MUS1C11L INSTRUMENTS.

APPLICATION FILED NOV. 4,1912.

Patented Nov. 11, 1913.

wvo. nto@ UNITED STATES PATENT OEETCE.

CHARLES W. DORRICOTT, F PHILADELPHIA, PENNSYLVANIA, ASSIGNOR T0 ELEC- TRELLE. COMPANY, OF SULMERDALE, PHILADELPHIA, PENNSYLVANIA, A CORPO- RATION OF PENNSYLVANIA.

specification' of Letters Patent.

Patented Nov. 11, 1913.

applicati@ med November 4,1912. serial No. 729,509.

T 0 all whom it may concern.:

Be itl known that I, CHARLES \V. DomucoTr, a citizen of the United States, residin at Philadelphia, in the county of PhiladeIphia and State of Pennsylvania, have 1n- -vented new and useful Improvements in Pneumato-Electric Trackerrlar's for Musical Instruments, of which the following 4is n specification.- I

My present invention relates tofcertain new and useful improvements in pneumato- ,electric trackers, designed amore especially for use in connection with electrically operated playing mechanism of musical instruments, such for instance as player pianos that` are controlled by perforated music sheets, and one of the prime objects of'my invention is to guard against fouling of the electrical contact; members, resulting from dust accumulations thereon or therebetween, which fouling renders the contact members inoperative or incapable of prop- .'erly closingr the electric. circuits leading to their associated electrically operated player actuating devices.

The present invention is in the nature of an improvement upon the pneumato-electric tracker shown and described iu my pending application tiled June 21, 1912, Serial Number 704,994.

I have discovered, after many experiments, that, perhaps the most serious dilli- Qulty encountered in these pneumato-elcctric ackers results from the accumulation upon and between the electric contact men'ilvers, of the tine particles of dust and lint coming from and through the perforated music sheets, as they travel over the tracker, and which foreign substances' soon become carbenizcd by reason of the electric sparks re sultinjY from the making and breaking ot the electric circuits between the contact members, and when such carbomzatlon takes place vthe contacts fail to properlyl transmit the electrical energy to the electrically operated playing mechanism, with the result that, said mechanism fails to respond when Called upon.

I have overcome the ditliculty mentioned hy-housing the electrical contact-'members in an air 'chambervor chestthat is entirely separate from, and has no communication with, the tracker ducts, and by providing a separate air chamber or chest into which the `hleedor v cnt holes from the electric contact-actuating pneumatics `lead, and into which latter named chamber or chest all the dust particles passing through the tracker ducts will be collected. Provision is also made for readily cleaning this chamber or chest, as well as the rent orbleed holes, when necessary. Y

In the present embodiment. of the invention I have shown my in'iprovements all in corporated in andv forming a part of a tracker bar structure that may be readily associated with bodily movable music roll holders of the type that are designed to be attached to the under side of the key-bed of a piano, so as to he moved from an operat' 'e position forward of the keys to an ineperative position back under the key-bed where the'music roll holder will be out of view.' I-,do not, however, wish to be understood as limiting myself to the exact embcdiment shown, as I am well aware that the invention may take other forms than the one shown, and may be applied to other than bodily movabh` music roll holders.

lli order to enable others skilled in the art to understand. malte` and msc my .said inventi.:n l will now provecd to lescrilm the same in detailreference bring had for this purpose to the accompanying drawings.v whereiiif Figure- 1 is a view of the tracker partly in plan and partlyviu horizontal section, the section beingr taken in two planes to show ditlcrent portions of the interior of the tracker structure. Fig. is a transverse vertical section taken on the line '2-2 of Fig. l.

lieferrilig to the drawing reference numeral 1 designatesA the face plat-e of the tracker bar having the usual duct openings` 2, the said faceplate having a relatively thick web extending from the rear face thereof, said web terminating in a portion 4 of reduced thickness or width, and the tracker ducts 2 extending longitudinally through the web, there being as inany tracker duct openings as there are notes to be sounded, or actuating devices 2 to be operated` The tracker bar 1 and its web portions v3 and 4 are preferably, but not necessarily, formed of metal, and each of the opposite faces of the portion 3 of the web is provided with two rows of recesses or pockets 5, cach of which recesses or pockets communicates by an opening 6 with one of the tracker ducts 2, as more clearly shown in- Fig. 1. The recesses or pockets 5 are preferably counterbored and each is covered by a tiexible diaphragm 7 held in place by means of a ring 8, the said 11i ngs 8 abutting'the shoulder of the recesses formed by the counterbore. The recesses or pockets 5 and their diaphragms 7 constitute pneumatics for actu-v ating the movable members of the electric contacts presently to be described. In order that the structure may be as compact as possible the rows of recesses or pockets 5 are offset relative to each other, as 'more clearly shown in Fig. 1. Y

Abutting the rear end of the reduced portion 4 of the web of the tracker is a channel plate 9 provided with a row of tapered bleed or vent holes 10, there being one such vent or bleed hole for each of the tracker ducts 2. Secured to the side walls 12 of the channel plate 9 is a rear cover plate 13, the space bounded by said channel plate 9 and cover plate 13 constituting what. I shall term a bleed lchamber 14, which chamber has couimunication by. means of a pipe 15 and conduit 16, with any suitable exhaus't apparatus,

such as the well-known exhaust pump usually employed in connection with pneumatic instruments. Y

The reference numerals 17 designate respectively the side lates of the tracker which are secured along t eir longitudinal edges to the opposite walls of the face plate 1 of the tracker, and the side walls 12 of the channel plate 9, respectively, the spaces between said plates 17 andthe opposite faces of the web portions 3 and 4 of the tracker constituting a. divided air chest or chamber 18, the divisions of` which have communication with each other at one end of the tracker, as more clearly shown in Fig. 1, and which chamber 18 -has communication with the conduit 16 by means of the pipe 16, The chamber 18, as well as the chamber 14, will, therefore, always be maintained under air tension or exhaust, and inasmuch as the bleed or'vcntholes 10 for the Pneumatics do not communicate with the chamber or chest 18, none of the dust particles passing through the tracker ducts 2 can find their way into said rhamberoruchest, but will be discharged into the chamber 1J( where the dust accumulations can be readily removed bv removing the end A plate 1?. \\'hen the plate 13 is removed the bleed or vent openings 10 will be exposed, and these may also be readily cleaned. Itis also possible with my construction to remove` the channel plate 9, in which the bleed 0r vent holes are formed, to enable these holes to he cleaned.

Secured to each sideof the reduced portion 4 of the web of the tracker is a strip 19 of wood or other insulating material, and to theV outer face of each of said strips is secun-d a plurality of movable contact fingers preferably made of thin strips of spring metal 21, there being one such movable contact finger for each of the pneumati. These movable` contact lingers are each secured at one end by means of a screw 22 to its strip 1 9, theother end overlying a disk or button .23 secured to the upper fa'ce of the diaphrag'ms 7. T he' movable contact fingers 21 are in circuit with the electrical playing mechanism (not shown), by means of the wires 21 leading from each of thesaidcontact tin gers, the said wires 21 being bunched in cable sections 25, which cable sections are arranged within the chamber 18 of the tracker, as more clearly shown in Fig. 1.

Coperativelyassociated with the free end of cach of the movable Contact fingers 21 is a stationary, but adjustable, contact pin 26, the lower end ot which is preferably pointed and ovcrlies, but is spaced from, the said free end of the movable contact finger, two rows of said pins passing through and having threaded coniieetionwvith each of the removable walls 17 of the tracker, and each pin havingan endA exposed outside t-he tracker bar that is provided with a screwdriver notch, or other tool engaging portion, whereby it may be readily turned to bring its-inner end in proper coperative adjust;- ment with its associated movable contact tinger without opening the tracker, a locknut Q7 being threaded on the exposed end of each pin to set the same after ad]ustment has been made. By reason of this construction the various contacts may be properly` adjusted after the'tracker parts have been assembled, and adjustment may also be made from time to time as occasion may require.

A tracker constructed in accordance with the. present invention is very compact; can be manufactured at relatively lowcost; is not liable to have its contact members become fouled or carbonized by reason of dust accumulations thereon or therebetween; and the contact members may be easily and quicklywuljusted from without the tracker; all of which are considerations of the greatwhere practicability depends almost entirely i ,ereg les upon proper actuation at all times of the Contact members and of each and every such member embodied in the structure, it being perfectly apparent to those skilled in the art that failure in the. operation of even one of the contact members-'of a series will render the entire instrument faulty.

lVhat I claim is 1.In a `pneumato-electrie tracker, aV

tracker-bar having the usual tracker-ducts, a plurality of pneumatics, one communicating with each duct, an air chamber in which said pneumatics are exposed, said chamber having no communication with the tracker d-ucts, cooperating electrical contacts in said chamber some of which are adapted to be actuated by said pne-umaties, a bleed chamber, and vent or bleed passages leading from the tracker ducts into said bleed chamber.

Q. In a '.pneumato-electric tracker, a tracker-bar having the usual tracker-ducts, a plurality of diaphragm pneumatics, one communicating with each duct., an air chamber in which the said diaphragm pneumatics are exposed, said chamber having no communication with the tracker ducts, electric contact lingers in said chamber adapted to be actuated by said pneumatics, electric Contact members with which said fingers coperate, a bleed cha-mber carried by the tracker and ventor bleed passages leading from the tracker ducts into said bleed chamber.

3. A pneumato-electric tracker comprising a tracker-bar having a Web extending from the rear wall thereof, said bar an webhaving tracker ducts extending therethrough, each duct having' a lateral-opening terminating in an enlarged recess covered by a flexible diaphragm, a chamber having no communication with the tracker ducts, electrical contact members arranged within said chamber and adapted to be brought intoelectrical connection by the bulging or lateral movement of the diaphragms from pneumatic action, a separate bleed-chamber forming a part of the tracker structure, and vent. or bleed passages leading from the tracker-ducts into said bleedchamber.

4. A pneumato-electric tracker comprising a hollow-member having the usual tracker ducts and an air chamber therein, said duc-ts having no communication with the chamber, a plurality of movable contact members mounted within the said chamber, pneumatics for actuating said contact members, said pneumaties being located Within the tracker and having communication with said duets, a pluralitytof xed contacts projecting through an outer wall of the tracker, said contacts being adjustahly mounted for eoaction with the said movable Contact members, a bleed-chamber forming a part nf the" tracker structure, and vent or bleed pas sages leading from the tracker ducts into said bleed chamber.

5. A pneufinato-electric tracker comprising a hollow member having the usual tracker ducts, and an air chamber, said duets having no communication with the chamber, a bleed chamber having bleed openings leading therein from the said tracker dncts,.said

bleed chamber being separate from the air chamber, a plurality of movable Contact members located within the said air chamber, pneumatics for actuating said contact members, said pneumatics being located within the tracker and having communication with said ducts, a plurality of fixedcontact pins projecting through an outer wail of the tracker into the said air chamber for coaction with the movable contact members, and means for adj ustably supporting said fixed contact pins.

6. A pneumato-electric tracker com rising a tracker-bar having` a web exten ing from the rear wall thereof, the rear portion of said web being of reduced thickness, said bar and web having tracker ducts extending therethrough, each duct having a lateral opening terminating in an enlarged recess covered by a flexible diaphragm, strips of insulating 9 material supported by the reduced portions of the web, achamber having no communication with'the tracker ducts, movable contact members arranged Within the chamber and each secured at one end to one of said strips and having its free end overlying one of the diaphragms to be actuated thereby, fixed contact members coperating with said movable contact members and having portions thereof exposed outside the tracker for adjustment, a bleed chamber forming a part of the tracker structure, and vent or bleed passages leading from the tracker ducts into said bleed chamber.

7. A pneumato-electric tracker comprising a tracker-bar having a web extending from the rear wall thereof, the rear portion of said web being of reduced thickness, said bar and web having tracker ducts extendin therethrough, each duct having a latera openinv terminating in an enlarged recess covere by a flexible diaphragm, strips of insulating material supported by the reduced portions of the web, a chamber having no communication with the tracker duets, movable contact members arranged within the chamber and each-secured at one end to one of said strips and having its free end overlying one of the diaphragn'is to be actuated thereby, fixed contact members cooperating with said movable contact memplate having bleed-openings registering with I my hnnd in presence of two subscribing wit- 'the several tracker duct-S, :i Cover for said i messes. channel )lute )rovidinfr a bleef chamber L )Y im y Y ,v and :in @.Ixhnusblconihlitnlving cmnmunicn? CLAIM D V" DOLLJCOI l' 5 tion respectively with the saidv biccfl and diaphragm clmn'rhcrs. I In testimony whcrcof 'I have hcrcunw et l W'i I ncsses A LnmT J. MILLERe Joux L. ConNoG. 

